diff --git a/securesystemslib/_gpg/common.py b/securesystemslib/_gpg/common.py
index d28cae95..d9989c29 100644
--- a/securesystemslib/_gpg/common.py
+++ b/securesystemslib/_gpg/common.py
@@ -385,8 +385,9 @@ def _assign_certified_key_info(bundle):
 
             if not is_valid:
                 log.info(
-                    "Ignoring invalid User ID self-certificate issued "
-                    "by '{}'.".format(signature["keyid"])
+                    "Ignoring invalid User ID self-certificate issued by '{}'.".format(
+                        signature["keyid"]
+                    )
                 )
                 continue
 
@@ -755,8 +756,7 @@ def parse_signature_packet(
     # Check whether we were actually able to read this much hashed octets
     if len(hashed_subpackets) != hashed_octet_count:  # pragma: no cover
         raise ValueError(
-            "This signature packet seems to be corrupted."
-            "It is missing hashed octets!"
+            "This signature packet seems to be corrupted.It is missing hashed octets!"
         )
 
     ptr += hashed_octet_count
diff --git a/securesystemslib/_gpg/eddsa.py b/securesystemslib/_gpg/eddsa.py
index 1bff5c02..043ebe16 100644
--- a/securesystemslib/_gpg/eddsa.py
+++ b/securesystemslib/_gpg/eddsa.py
@@ -79,8 +79,7 @@ def get_pubkey_params(data):
     # See 9.2. ECC Curve OID
     if curve_oid != ED25519_PUBLIC_KEY_OID:
         raise PacketParsingError(
-            f"bad ed25519 curve OID '{curve_oid}', "
-            f"expected {ED25519_PUBLIC_KEY_OID}'"
+            f"bad ed25519 curve OID '{curve_oid}', expected {ED25519_PUBLIC_KEY_OID}'"
         )
 
     # See 13.3. EdDSA Point Format
diff --git a/securesystemslib/_gpg/util.py b/securesystemslib/_gpg/util.py
index 5a07416c..7a62d081 100644
--- a/securesystemslib/_gpg/util.py
+++ b/securesystemslib/_gpg/util.py
@@ -192,7 +192,7 @@ def parse_packet_header(data, expected_type=None):  # noqa: PLR0912
 
         elif length_type == 3:
             raise PacketParsingError(
-                "Old length " "format packets of indeterminate length are not supported"
+                "Old length format packets of indeterminate length are not supported"
             )
 
         else:  # pragma: no cover (unreachable)
diff --git a/tests/check_public_interfaces_gpg.py b/tests/check_public_interfaces_gpg.py
index ff82dfb2..f8b2fca1 100644
--- a/tests/check_public_interfaces_gpg.py
+++ b/tests/check_public_interfaces_gpg.py
@@ -39,9 +39,9 @@
 class TestPublicInterfacesGPG(unittest.TestCase):
     @classmethod
     def setUpClass(cls):
-        assert (
-            not have_gpg()
-        ), "please remove GnuPG from your environment to run this test case"
+        assert not have_gpg(), (
+            "please remove GnuPG from your environment to run this test case"
+        )
 
     def test_gpg_functions(self):
         """Signing, key export and util functions must raise on missing gpg."""
diff --git a/tests/test_gpg.py b/tests/test_gpg.py
index 62b5b409..cca33f5b 100644
--- a/tests/test_gpg.py
+++ b/tests/test_gpg.py
@@ -693,7 +693,7 @@ def test_verify_signature_with_expired_key(self):
         )
         self.assertTrue(
             expected == str(ctx.exception),
-            f"\nexpected: {expected}" "\ngot:      {ctx.exception}",
+            f"\nexpected: {expected}\ngot:      {{ctx.exception}}",
         )